薄膜激光损伤中的等离子体液滴膨胀过程

Expansion Process of Plasma Drop in Laser Induced Damage

实验中,长脉冲激光作用下的薄膜破坏常伴随着等离子体闪光,该闪光是等离子体在向外空间膨胀消耗能量时所发出的弧光。从高密度等离子体液滴膨胀过程的运动学、动力学、热力学过程出发,分析了等离子体液滴膨胀过程中的液滴半径、电子加热速率、电子密度、电子温度、离子温度等随时间演化的情况。分析认为等离子体膨胀引起的电子密度变化会影响其对激光能量的吸收速率,从而影响电子、离子温度,进而影响等离子体膨胀速度。这些影响也必将延伸到等离子体对薄膜表面的冲击压力中去,对薄膜激光损伤过程的后期分析具有重要的意义。

On the role of the long-pulsed laser, plasma flash phenomenon can be observed in films damage experiment. This phenomenon is the result of plasma expansion to the outer space and in this process the energy is consumed by the irradiation of arc. From the kinematics, dynamics, and thermodynamics of the expansion process of high-density plasma droplets, the evolution of radius, electronic absorption rate, electron density, electronic temperature, and ion temperature of droplet in the process of the plasma expansion have been investigated. The results reveal that the change of electron density caused by plasma expansion will affect its absorption rate of laser energy. This phenomenon can affect electronics temperature, ion temperature, and the rate of plasma expansion. These effects are of great significance when they are extended to the latter part of the analysis of the plasma impact wave during laser induced films damage.